Debarking method and apparatus

ABSTRACT

Tree limb sections to be debarked and a plurality of smaller, higher density impact objects are disposed in a series of interconnected generally cylindrical rotating chambers which are tilted at a slight horizontal angle and are serially offset in the radial direction relative to the preceding chamber for cascading the impact objects and wood sections through the chambers in seriatum and for discharging the same from the final chamber. Material handling means collect the impact objects after discharge from the final chamber for recycling the initial chamber.

United States Patent Smiltneek July 29, 1975 DEBARKING METHOD AND APPARATUS [76] Inventor: Ralmond J. Smiltneek, 12906 w. j;

Falrmoum Butler 53007 Attorney, Agent, or FirmFred Wiviott [22] Filed: July 3, 1974 [21] Appl. No.: 485,500 [57] ABSTRACT Tree limb sections to be debarked and a plurality of Cl 144/311; 4/20 smaller, higher density impact objects are disposed in 241/181 a series of interconnected generally cylindrical rotat- Int. chambers are tilted at a horizontal Field of Search l44/208 R, 208 31 1; angle and are serially offset in the radial direction rel- ,1 183, 181 ative to the preceding chamber for cascading the impact objects and wood sections through the chambers [56] Ref r n es C d v in seriatum and for discharging the same from the UNITED STATES PATENTS final chamber. Material handling means collect the 2 324 700 2/1958 Weston 241/171 x impact Objects after discharge from the final Chamber 3,272.245 9/1966 Dick et al..... 144/208 B for recycling the initial chamber- 3,746,063 7/1973 Smiltneek 144/208 B 3.837.490 9/1974 Driebel et al. 241/178 x 26 Clams 9 D'awmg F'gures so i 29 PATENTEB JUL 2 9 I975 SHEET DEBARKING METHOD AND APPARATUS BACKGROUND OF THE INVENTION This invention relates to method and apparatus for debarking tree sections.

There is a substantial need for fuller utilization of pulp wood in view of increasing demand and resource limitations. At present, processing losses may account for up to 70% of a tree cut. To a substantial degree. these losses have resulted from the difficulty in utilizing tree limbs and top sections due to the lack of an efficient and economical debarking method and apparatus. In the pulp and paper industry, efficient bark removal is especially important because only small quantities of bark can be tolerated in the pulp mixture. For example. approximately 4% is the upper limit of bark content that will be accepted by most pulp mills. Because most prior art methods for debarking tree limb and top sections were not wholly satisfactory, these tree portions are generally left at the cutting site to rot.

One prior art debarking apparatus is disclosed in US. Pat. No. 3,746,063 which relates to a rotatable chamber in which tree sections to be debarked and a plurality of higher density impact objects are contained. The impact objects are thereby caused to randomly impact the tree sections so that bark separation is effected. The apparatus and method disclosed in said patent while effective for bark separation, is essentially a batch process.

SUMMARY OF THE INVENTION It is a general object of the invention to provide improved debarking method and apparatus.

Another object of the invention is to provide a debarking apparatus and method particularly adapted to debark tree limbs and top sections.

A further object of the invention is to provide a substantially continuous flow debarking method and apparatus.

A further object of the invention is to provide a debarking apparatus and method which is not dependent on the shape of the tree segments being debarked and which may be employed at the cutting site.

These and other objects and advantages of the instant invention will become more apparent from the detailed description thereof taken with the accompanying drawmgs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of the apparatus according to the invention;

FIG. la is a view taken along lines Ia-la of FIG. 1;

FIG. 2 is a side elevational view of a portion of the apparatus shown in FIG. 1;

FIG. 3 is a view taken along lines 33 of FIG. 2;

FIG. 3a is a fragmentary view showing a portion of the evacuation duct of the apparatus shown in FIG. 1;

FIG. 4 is a view taken along lines 4-4 of FIG. 3 with parts broken away;

FIG. 5 is a view taken along lines 55 of FIG. 2;

FIG. 6 is a view taken along lines 66 of FIG. 5; and

FIG. 7 is a view taken along lines 77 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. I and 2 show the invention generally to include a plurality of substantially identical debarking chambers 10, 11 and 12 which are independently mounted for rotation on a suitable support which may comprise, for example, a flat bed trailer 14. The chambers 10, 11 and 12 are oriented for rotation about generally parallel axes which are offset radially relative to the next adjacent chamber. As will be discussed more fully below, the rotational axis of each chamber is tilted slightly in the same direction to promote migration through the system of tree sections being debarked.

The chambers 10, I1 and 12 are each generally hollow and interconnected in any suitable manner such as by a first hollow stationary metallic cowl 16 disposed between the output side of chamber and the input side of chamber 11 and a second hollow stationary and metallic cowl 18 disposed between the outlet side of chamber 11 and the inlet side of chamber 12. In addition, an infeed chute 20 is coupled to the inlet side of chamber 10 through stationary metallic cowl 21 and a discharge chute 23 is coupled to the outlet side of chamber 12 through a stationary hollow metallic cowl 25. The cowls 16, 18, 21 and 25 may be fixedly mounted on trailer 14 in any suitable manner, not shown, but which is well known in the art.

An air evacuation system 28 (FIG. 1) is coupled to each of the cowls l6, l8 and 20 for inducing an air stream into each of the chambers 10, 11 and 12 for removing the dislodged bark. Mounted at the end of the trailer 14 is a power unit 29 for driving a suction fan 30 coupled to the air system 28 and for rotating the chambers 10, 11 and 12. The power unit 29 also operates a material handling system 32 (FIG. 2) for receiving impact objects from the last chamber 12 for recycling the same to the first chamber 10.

As indicated hereinabove, each of the chambers 10, 1 l and 12 are substantially identical and, accordingly, only chamber 10 will be discussed in detail for the sake of brevity. As seen in FIGS. 3 and 4, chamber 10 comprises an outer cylindrical shell which is open at its opposite ends to define a circular inlet opening 41 for receiving wood sections 42 to be debarked and impact objects 43. The opposite open end 44 of chamber 40 defines a discharge opening for transmitting the wood sections 42 and impact objects 43 into the next adjacent chamber 11. A plurality of longitudinally extending vanes 45 are suitably affixed on the interior of the chamber 40 for circulating the wood sections 42 and the impact objects 43 as the shell rotates.

As viewed in FIG. 3, the shell 40 is mounted for counterclockwise rotation about a generally horizontal axis. More specifically, the shell 40 is mounted on two pair of friction wheels 46 and 47. The friction wheels 46 engage the shell 40 and are affixed to a drive shaft 48 which is journaled for rotation on spaced apart brackets 49, 50 and 51 extending upwardly from and affixed to trailer 14. It can also be seen that the drive wheels 47 which rotatably support the shell of the next adjacent chamber 11 are also affixed to drive shaft 48. In a similar fashion, drive wheels 46 and 47" of chambers l1 and 12 respectively are each mounted on shaft 48' and drive wheels 46" of chamber 12 are mounted on shaft 48". Motive power is transferred from power unit 29 to the respective chamber drive wheels by means of a drive shaft 52 journaled for rotation about a generally horizontal and longitudinal axis relative to the trailer 14 by means of suitable bearings, not shown, but which may be mounted above trailer 14 in any well known manner. A plurality of beveled pinion gears 54,

55 and 56 are affixed to shaft 52 for engaging driven bevel gears 60, 61 and 62 which are respectively mounted on the ends of shafts 48, 48 and 48". It will be appreciated that the end of shaft 52 is coupled to a gear reduction mechanism 64 (FIG. 1) which forms a part of power unit 29 whereby rotation of the shaft 52 will simultaneously rotate each of the chambers 10, 11 and 12 in a common direction and at substantially the same speed. As can be seen in FIG. 4, the ends of the cowls l6 and 21 overlap the edges of the shell 40 and to facilitate rotation, suitable bearings (not shown) may be disposed therebetween.

The second pair of drive wheels 47 of chamber 10 affixed to shaft 52 which is journaled for rotation on support brackets 53 suitably supported on trailer 14. The wheels 47 may either idle as the chamber 10 rotates or shaft 52 may be driven by means of sprockets 54 and 55 which are respectively affixed to shafts 48 and 52 which may be interconnected by means of a chain 56.

The chute 23 may take any convenient form such as a semicylindrical, generally horizontally extending metallic section whose lower side is open for encompassing a generally horizontally extending vibratory screen 70. The chute 23 has a first end 72 which is coupled to the cowl 25 which in turn opens into the last chamber 12 and an opposite end 73 which is open. The apparatus for supporting and vibrating the screen 70 forms no part of the instant invention and, accordingly, will not be discussed in detail for the sake of brevity. Those skilled in the art will appreciate that such vibration motion may be imparted in any suitable manner such as by means of an electromagnetic vibrator or any suitable mechanism coupled to shaft 52 and which is operative to transform rotary motion into reverbatory longitudinal motion. It is sufficient for purposes of understanding the present invention to state the screen 70 vibrates in a generally horizontal direction and between the ends 72 and 73 of the chute 23 for moving wood sections 42 which discharge from chamber 12 toward the open end 73. To facilitate such motion, the screen may be tilted slightly from its front to its rear end. The openings in screen 70 are larger in size than the impact objects 43 so that the objects which discharge from chamber 12 onto screen 70 will fall through said screen and onto an endless conveyor belt 75 disposed therebelow. Belt 75 extends over a pair of spaced apart rollers 76 which are suitably journaled for rotation on bracket 77 extending upwardly from trailer 14. One of the rollers 76 may be coupled to the drive shaft 52 by means not shown but which are well known in the art for clockwise rotation as viewed in FIG. 2 so that the upper surface of the belt 75 moves from the chute 23 toward the inlet 20. The surface of the belt 75 may have a plurality of lugs 78 formed thereon to assist in movement of the impact objects 43 and other waste material which may fall through the screen 70.

Disposed at the front end of the assembly is a recycling ring 80 which is shown in FIGS. 2 and to be mounted eccentrically with respect to chamber by means of support rollers 82 which are suitably mounted for rotation on trailer 14. One or more of the support rollers 82 may be coupled to the power unit 29 by means (not shown) for rotating ring 80.

Ring 80 is rotated at a speed sufficient to cause the impact objects 43 to be held against the outer portions of ring 80 by centrifugal force until they rise to a point where gravity overcomes that force. As seen in FIG. 6,

ring 80 is generally V-shaped in cross section and its sides diverge inwardly toward its rotational axis and a plurality of fins 82 extend between the inner surfaces of the sides to form pockets for carrying the impact objects 43 upwardly.

A generally semi-circular, stationary guide member 85 is disposed adjacent the recycling ring 80 and extend above the belt to a second point generally above the center of the inlet opening of chamber 10. As seen in FIGS. 5 and 7, a first portion 86 of member 85 extends diagonally across belt 75 for being engaged by the impact objects 43 as the belt 75 moves therebelow whereby the impact objects 43 are directed into the recycling ring which is disposed below belt 75 at its point of intersection with portion 85. A second portion 88 of ring is disposed closely adjacent the ring 80 and extends across the open side thereof to prevent the impact objects 43 from falling out of ring 80 whenever ring 80 is run slower than its normal speed such as during start-up and shutdown. The upper terminal portion 90 of member is generally channel shaped and curves downwardly and inwardly toward the inlet end of chamber 10 to direct the impact objects into said chamber as they fall away from ring 80.

Each of chambers 10, 11 and 12 is preferably tilted slight toward the left as viewed in FIG. 2 and from their lower to their upper ends. Accordingly, as chambers 10, 11 and 12 rotate, wood section 42 and impact objects 43 disposed in the chambers tend to to migrate from the inlet end of chamber 10 to discharge chute 23.

The air evacuation system 28 includes a duct 94 and extends from the fan 30 and in general parallelism with the trailer 14. Each of the cowls 16, 18 and 19 has an opening 96 formed on corresponding sides of the assembly and each is coupled to the duct 94 by a short duct section 97. The openings 96 are formed adjacent the lower ends of the respective cowls and on the side relative to the direction of rotation of chambers l0, l1 and 12 such that the openings are in the region where the impact objects 43 and wood sections 42 are moving downwardly. In addition, the short duct section 97 extends upwardly and is generally curved in a direction opposite to that of the cowls 16, 18 and 19. A second opening 98 is formed in each cowl 21, 16, and 18 in an opposed relation to the openings 96 formed in cowls 16, 18 and 25 respectively and each may be covered by a suitable screen. When the fan 30 is operated to draw air through openings 98, lighter material such as bark, leaves, and dirt moving past openings 96 in a downward direction will be drawn upwardly through ducts 97 and through the exhaust duct 94 while the heavier wood sections and impact objects will fall past such openings. Any suitable separator 99 may be disposed between the fan 30 and the duct 94.

The chute 20 has an open top and its lower end tilts downwardly toward the inlet if chamber 10. A suitable infeed conveyor 104 may be disposed with its discharge end above chute 20 so that wood sections 42 and impact objects 43 which are delivered by conveyor 104 to chute 20 will be charged into chamber 10.

In operation of the assembly, the power unit 29 is energized to begin rotation of the chambers 10, 11 and 12 as well as the input feed conveyor 104, the recycling conveyor 75 and the vibrating screen 70. A plurality of wood sections 42 to be debarked are disposed on the infeed conveyor 104 for delivery to the chute 20 which discharges the wood sections into the first chamber 10.

At the same time. impact objects 43 are delivered to chamber as the recycling wheel 80 rotates. The wood sections 42 and impacting objects 43 are circulated in chamber 12 by the vanes 45 upwardly and toward the center of the chamber as shown in FIG. 3. It will be appreciated that the height to which the objects 43 and wood sections 42 are raised within the chamber 10 will, to some extend, be dictated by the speed of rotation. It will be appreciated, therefore, that the speed of chamber 10 should be sufficiently great to carry the objects to the upper end of the chamber but less than the critical centrifugal speed which would tend to hold the wood sections 42 or the impact objects 43 against the surface of chamber 10. About 70% of this critical speed has been found to be satisfactory. The impact ob jects 43 should generally have a density several times greater than the wood sections 42 and are preferably substantially smaller in size. Although the impact objects 43 and the wood sections 26 may move through the same general pathways, virtually all the work of debarking is delivered by the impact objects 43 because of their relatively high density relative to the wood. Each piece of wood 42 receives generally uniformly and randomly distributed surface impacts and abrasions from the impact objects 43. If the unit impact energy lies above the critical level determined by wood specie and condition, the gradual and uniform degrading of the bark structure occurs whereby the bond between the bark and wood is uniformly weakened and the bark is soon stripped away.

Because of the slight tilt to chamber 10, the wood sections 42 and impact objects 43 tend to migrate toward chamber 11 and eventually said wood sections and impact objects are moved into chamber 11 where the debarking process continues. Similarly, the tilt of chamber 11 will tend to move the wood sections 42 and impact objects 43 toward chamber 12 where the debarking process continues further and finally the tilt of chamber 12 will move the wood sections and impact objects onto the vibrating screen 70. The repeated and random impacts of the objects 43 and the wood sections 42 will tend to eventually remove all of the bark as the wood sections move through chambers 10, 11 and 12. As the bark is thus removed, the air blast extending across each of the chambers and between openings 96 and 98 will tend to discharge the dislodged bark from the system where it may be conveniently collected and disposed of.

As the wood sections 42 and impact objects 43 pass onto the screen 70, the vibration of the latter tends to move the wood sections 42 out the discharge end 73 of chute 23. The impact objects 43 fall through openings in the screen onto the recycling conveyor belt 75 along with dirt and other waste particles not removed by the air system. Conveyor belt 75 moves the impact objects toward the recycling ring 80 where the objects engage the portion 86 of member 85 for being dislodged onto the recycling ring 80 passing therebelow. The dirt and other waste material, however, of smaller size, pass below the portion 86 for being discharged. The rotating recycling ring 80 carries the impact objects upwardly for redelivering the same to the first chamber 10.

The specie, age, and condition of the Wood sections to be treated determines the dwell time in the apparatus which may be necessary in order to completely debark the wood sections 42. As indicated above, the wood sections 42 migrate through the apparatus as a result of the tilt of the individual chambers 10, 11 and 12. In order to adjust this dwell time as may be desirable for particular wood sections, the flatbed I4 is made adjustable by means of a universally adjustable fifth wheel (not shown) which couples one end of trailer bed 14 to a tractor (FIG. 1) and a pivotal coupling 112 at the other. The coupling 112 is shown in FIG. 1a to include a first semiannular member I14 which is affixed to trailer bed 14 and a second. substantially identical member affixed to a truck I16. The members 114 and 115 are held in an abutting relation to secure bed 14 to truck 116 by means of bolts 118 and nuts 119 which extend through elongate, registerable slots 120 formed in said members. Spring washers (not shown) may be provided between bolts 118 and one of the members 114- or 115 to hold said members in resilient sliding engagement. A dual acting hydraulic cylinder 122 is suitably mounted on member 114 and has an extensible rod 123 which engages a dog 124 mounted on member 115. When the cylinder 122 is pressurized through one of its ends through couplings 125 or 126 from a source of hydraulic pressure (not shown), the trailer bed 14 will be caused to rock in one direction or the other. This causes the chambers 10, 11 and 12 to rock about an axis which is at an angle to thin axes of rotation to simultaneously increase or decrease the tilt of said chambers. If after originally setting the tilt angle, the operator determines that the dwell time is too long or too short, the tilt may be readjusted. Also, after wood sections 42 have migrated part way through the apparatus, the chambers 10, 11 and 12 may be tilted back to cause a rearward flow of wood sections 42 for a predetermined time after which the tilt angle would again be changed to the forward direction so as to resume the forward flow direction. In this manner, the dwell time can be increased to any given value to effect complete debarking. The trailer bed 14 will normally be centered and the nuts 119 tightened for travel.

It will be appreciated from the foregoing that the system provides a continuous debarking process and apparatus wherein the wood sections 42 are delivered to one end of the system and debarked wood sections delivered from the other while the impact objects 43 are recirculated. While three impacting chambers 10, 11 and 12 are illustrated, it will be appreciated that the number will be determined by the difficulty and number of impacts necessary to debark a particular wood section, the desired system capacity and the speed that the wood sections migrate through the system, the latter of which is also dependent to some extent upon the angle of tilt of individual debarking chambers. The continuous process illustrated permits the debarking of wood sections without sorting or recycling and permits total debarking while maintaining the entrance to exit distance relatively short. It will also be appreciated that the number of individual rotating debarking chambers determines the overall capacity of the system with an increase in the number of chambers resulting in an increased capacity.

For many species of wood there is a definite difference between the bark breakdown energy and the wood breakdown energy. If the chamber 10 is operated somewhere between the two critical energy levels, suitable rapid destruction on the bark will occur with relatively little damage to the wood.

Because the process exposes the surface of the wood pieces to uniformly distributed energy delivery, their roundness and symmetry of the wood is not important and shape becomes relatively insignificant. irregularly shaped wood pieces are efficiently debarked with very little loss of wood fiber. Effective debarking can therefore be achieved regardless of sizes and shapes of tree sections available or the apparatus for cutting the sections. A practical wood section length is about 12 to 24 inches although lengths shorter or longer may be employed. Similarly, the cross sectional dimensions of the wood can vary widely but preferably the sections should be in the range of 2 to 10 inches.

The action within the chambers 10, 11 and 12 is mainly selective abrading, crushing and shearing of the bark in preference to the wood fiber. This preferential action is enhanced by the fact that most bark is normally more brittle than the wood it is associated with and hence more susceptible to impact crushing.

The size, shape, hardness and energy level of the impacting objects may vary widely. Examples of impacting objects which were found to be satisfactory were mild steel slugs having generally cubicle, cylindrical or disc-like shapes about a cubic inch in volume. These were employed in a rotating chamber of approximately 6 feet in diameter at about 80 percent of critical speed and were found to be effective for rapidly abrading and removing bark from three inch diameter aspen wood. Also, typical ceramic or metallic materials used in ball mills or even stones can be employed. It will be understood that the terms stones as used herein means both natural stones and crushed rock.

The debarked wood produced in the process will generally be sufficiently clean for chipping into wood pulps or flaking for particle board use. The process provides an efficient and economical method for debarking limbs and treetop sections which are normally now discarded. This not only provides an economical use for tree sections which have heretofore been discarded, but also allows the use of trees which were heretofore not usable because of size or shape.

Those skilled in the art will appreciate that the apparatus and method according to the invention may also be applied for the removal of any undesired matter from wood sections. For example, plaster could be removed from wood salvaged from demolished buildings, rot could be removed from log sections and bark from sawmill slabs. Also whole logs could be debarked by merely modifying vanes 45 and the cowls between chambers so that the log rotated whereby the impact objects 43 could randomly engage its surface.

While only a single embodiment of the invention has been disclosed and described, it does not intend to be limited thereby but only by the scope of the appended claims.

I claim:

1. Apparatus for debarking wood sections comprisa plurality of means each defining a chamber, each of said chambers being mounted for rotation about generally parallel axes, each of said chambers being generally hollow, and hollow means interconnecting said chambers in a series relation,

means for simultaneously rotating each of said chambers,

a plurality of unconnected impact means each having a higher specific gravity than the wood sections to be debarked.

means disposed within each of said chambers for moving said plurality of impact means within said impact zone a distance substantially greater than the largest dimension of the impact means for randomly impacting the wood sections with the impact means whereby the bark on said sections is removed.

2. The apparatus set forth in claim I wherein the rotational axis of each succeeding chamber in said series is offset radially with respect to the rotational axis of the next preceding chamber.

3. The apparatus set forth in claim 2 and including inlet means disposed adjacent the first of said series of chambers for directing wood sections and impact objects into said first chamber and discharge means for receiving debarked wood sections and impact means from the last of said series of chambers.

4. The apparatus set forth in claim 3 and wherein said impact means comprise impact objects including recycling means for receiving the impact objects discharging from the last chamber in the series and for recirculating said impact objects to the first of said series of chambers.

5. The apparatus set forth in claim 4 wherein each of said rotational axes of each of said chambers are tilted in the same direction to promote migration of the wood section and impact objects through said chambers.

6. The apparatus set forth in claim 5 and including air delivery means for delivering an air blast across at least some of said plurality of chambers for removing dislodged bark therefrom.

7. The apparatus set forth in claim 6 wherein said discharge means includes vibrating screen means disposed adjacent the outlet of the last of said series of chambers, the openings in said screen means being larger than said impact objects, conveyor means passing below said screen means for reconveying the impact objects to the inlet of the first chamber of said series, and means for removing the impact objects from said conveyor means and for delivering the same to the interior of said first chamber.

8. The apparatus set forth in claim 7 and including drive means associated with each of said chambers for rotating the same, and motive means common to each of said drive means for simultaneously driving each of said chambers.

9. The apparatus set forth in claim 8 wherein said impact objects have a smaller size than said wood sections.

10. The apparatus set forth in claim 2 wherein each of said rotational axes are tilted in the same direction to promote migration of the wood section and impact means through said chambers.

11. The apparatus set forth in claim 2 and including air delivery means for delivering an air blast across at least some of said plurality of chambers for removing dislodged bark therefrom.

12. The apparatus set forth in claim 2 and including discharge means having vibrating screen means disposed adjacent the outlet of the last of said series of chambers, said screen means having openings larger than that of said impact means, conveyor means passing below said screen means for reconveying the impact means to the inlet of the first chamber, and means for removing the impact means from said conveyor means and for delivering the same to the interior of the said first chamber of said series.

13. The apparatus set forth in claim 2 and including drive means associated with each of said chambers for rotating the same, and motive means common to each of said drive means for simultaneously driving each of said chambers.

14. The apparatus set forth in claim 2 and including means for simultaneously pivoting each of said chambers about an axis lying in a plane which intersects the rotational axis of said chambers at an acute angle whereby said chambers may be simultaneously tilted to change the dwell time of wood sections therein.

15. The apparatus set forth in claim 14 and including inlet means disposed adjacent the first of said series of chambers for directing wood sections and impact means into said first chamber and discharge means for receiving debarked wood sections and impact means from the last of said series of chambers.

16. The apparatus set forth in claim 15 and including recycling means for receiving the impact means discharging from the last chamber in the series and for recirculating said impact objects to the first of said series of chambers.

17. The apparatus set forth in claim 16 and including air delivery means for delivering an air blast across at least some of said plurality of chambers for removing dislodged bark therefrom.

18. A method of removing undesirable material from wood sections comprising the steps of:

providing a plurality of interconnected impact zones,

placing in the first of said impact zones a plurality of unconnected impact means having higher specific gravity than the wood sections to be debarked, introducing into a first impact zone at least one of said wood sections,

rotating each of said impact zones for continuously separating said impact means and said wood sections and randomly moving said plurality of impact means relative to said wood sections and into impacting engagement therewith,

moving said wood sections and impact means successively through each of said zones while rotating the same to randomly move the impact means relative to the wood sections and into impacting engagement therewith,

removing the wood sections and impact means from the last of said zones, recycling said impact means to the first of said zones,

and introducing additional wood sections into the first of said zones.

19. The method set forth in claim 18 wherein said undesirable material comprises bark, said impact means comprises a plurality of individual objects having a substantially smaller size than said wood sections. and including the steps of containing a plurality of said sections in said zone. and moving said objects along a path whose length is at least several times greater than the largest dimension of said objects.

20. The method set forth in claim 19 wherein said impacting zones comprise chambers and rotating said chambers about a substantially horizontal axis for moving said impact objects into engagement with said wood sections.

21. The method set forth in claim 20 and including the step of rotating said chambers at a rate sufficient to raise said objects above said substantially horizontal axis prior to release.

22. The method set forth in claim 21 and including the step of inclining said chambers through substantially the same angle to promote migration of said wood sections therethrough.

23. The method set forth in claim 22 wherein said objects comprise a metallic material.

24. The method set forth in claim 22 wherein said objects comprise a ceramic material.

25. The method set forth in claim 22 wherein said objects comprise stones.

26. The method set forth in claim 22 and including the step of inducing an air stream across each of said chambers for removing separated bark from said impacting Zone. 

1. Apparatus for debarking wood sections comprising: a plurality of means each defining a chamber, each of said chambers being mounted for rotation about generally parallel axes, each of said chambers being generally hollow, and hollow means interconnecting said chambers in a series relation, means for simultaneously rotating each of said chambers, a plurality of unconnected impact means each having a higher specific gravity than the wood sections to be debarked, means disposed within each of said chambers for moving said plurality of impact means within said impact zone a distance substantially greater than the largest dimension of the impact means for randomly impacting the wood sections with the impact means whereby the bark on said sections is removed.
 2. The apparatus set forth in claim 1 wherein the rotational axis of each succeeding chamber in said series is offset radially with respect to the rotational axis of the next preceding chamber.
 3. The apparatus set forth in claim 2 and including inlet means disposed adjacent the first of said series of chambers for directing wood sections and impact objects into said first chamber and discharge means for receiving debarked wood sections and impact means from the last of said series of chambers.
 4. The apparatus set forth in claim 3 and wherein said impact means comprise impact objects including recycling means for receiving the impact objects discharging from the last chamber in the series and for recirculating said impact objects to the first of said series of chambers.
 5. The apparatus set forth in claim 4 wherein each of said rotational axes of each of said chambers are tilted in the same direction to promote migration of the wood section and impact objects through said chambers.
 6. The apparatus set forth in claim 5 and including air delivery means for delivering an air blast across at least some of said plurality of chambers for removing dislodged bark therefrom.
 7. The apparatus set forth in claim 6 wherein said discharge means includes vibrating screen means disposed adjacent the outlet of the last of said series of chambers, the openings in said screen means being larger than said impact objects, conveyor means passing below said screen means for reconveying the impact objects to the inlet of the first chamber of said series, and means for removing the impact objects from said conveyor means and for delivering the same to the interior of said first chamber.
 8. The apparatus set forth in claim 7 and including drive means associated with each of said chambers for rotating the same, and motive means common to each of said drive means for simultaneously driving each of said chambers.
 9. The apparatus set forth in claim 8 wherein said impact objects have a smaller size than said wood sections.
 10. The apparatus set forth in claim 2 wherein each of said rotational axes are tilted in the same direction to promote migration of the wood section and impact means through said chambers.
 11. The apparatus set forth in claim 2 and including air delivery means for delivering an air blast across at least some of said plurality of chambers for removing dislodged bark therefrom.
 12. The apparatus set forth in claim 2 and including discharge means having Vibrating screen means disposed adjacent the outlet of the last of said series of chambers, said screen means having openings larger than that of said impact means, conveyor means passing below said screen means for reconveying the impact means to the inlet of the first chamber, and means for removing the impact means from said conveyor means and for delivering the same to the interior of the said first chamber of said series.
 13. The apparatus set forth in claim 2 and including drive means associated with each of said chambers for rotating the same, and motive means common to each of said drive means for simultaneously driving each of said chambers.
 14. The apparatus set forth in claim 2 and including means for simultaneously pivoting each of said chambers about an axis lying in a plane which intersects the rotational axis of said chambers at an acute angle whereby said chambers may be simultaneously tilted to change the dwell time of wood sections therein.
 15. The apparatus set forth in claim 14 and including inlet means disposed adjacent the first of said series of chambers for directing wood sections and impact means into said first chamber and discharge means for receiving debarked wood sections and impact means from the last of said series of chambers.
 16. The apparatus set forth in claim 15 and including recycling means for receiving the impact means discharging from the last chamber in the series and for recirculating said impact objects to the first of said series of chambers.
 17. The apparatus set forth in claim 16 and including air delivery means for delivering an air blast across at least some of said plurality of chambers for removing dislodged bark therefrom.
 18. A method of removing undesirable material from wood sections comprising the steps of: providing a plurality of interconnected impact zones, placing in the first of said impact zones a plurality of unconnected impact means having higher specific gravity than the wood sections to be debarked, introducing into a first impact zone at least one of said wood sections, rotating each of said impact zones for continuously separating said impact means and said wood sections and randomly moving said plurality of impact means relative to said wood sections and into impacting engagement therewith, moving said wood sections and impact means successively through each of said zones while rotating the same to randomly move the impact means relative to the wood sections and into impacting engagement therewith, removing the wood sections and impact means from the last of said zones, recycling said impact means to the first of said zones, and introducing additional wood sections into the first of said zones.
 19. The method set forth in claim 18 wherein said undesirable material comprises bark, said impact means comprises a plurality of individual objects having a substantially smaller size than said wood sections, and including the steps of containing a plurality of said sections in said zone, and moving said objects along a path whose length is at least several times greater than the largest dimension of said objects.
 20. The method set forth in claim 19 wherein said impacting zones comprise chambers and rotating said chambers about a substantially horizontal axis for moving said impact objects into engagement with said wood sections.
 21. The method set forth in claim 20 and including the step of rotating said chambers at a rate sufficient to raise said objects above said substantially horizontal axis prior to release.
 22. The method set forth in claim 21 and including the step of inclining said chambers through substantially the same angle to promote migration of said wood sections therethrough.
 23. The method set forth in claim 22 wherein said objects comprise a metallic material.
 24. The method set forth in claim 22 wherein said objects comprise a ceramic material.
 25. The method set forth in claim 22 wherein said objects comprise stones.
 26. ThE method set forth in claim 22 and including the step of inducing an air stream across each of said chambers for removing separated bark from said impacting zone. 